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The Atlas moth (Attacus atlas) is a large moth belonging to the Saturniidae family. Saturniids, familiarly called giant silk moths, include some of the largest species of Lepidoptera (moths and butterflies). Two local species that may be familiar to readers are the polyphemus and luna moths.

Atlas moths are considered the largest moths in the world in terms of total wing surface area. Their wingspans are also among the largest, often reaching over 10 inches. They are strikingly beautiful, with tawny wings punctuated with translucent “windows” bordered by black. Their most distinguishing feature (other than their size) is an extension of their forewings that resembles a snake’s head, thought to be a means of scaring off potential predators.

These spectacular moths make superb additions to the Cockrell Butterfly Center. During the day, they spend most of their time motionless, clinging to the side of a tree or other surface. Visitors can thus get up close to intimately study these creatures, and can clearly observe their fat, furry bodies, fuzzy antennae, and teddy bear like expressions.

Once night falls, the male Atlas moths take flight in search of a female. The search has a sense of urgency, as adult Atlas moths typically live only about one week. This is because the adults do not have fully formed mouth parts and therefore cannot eat; they are sustained only by the fat reserves they built up as a caterpillar. The moths will quickly mate, lay eggs, and die soon after.

One day at the Cockrell Butterfly Center, a male and female emerged from their cocoons around the same time. We took the opportunity to breed and raise this species of moth. The newly emerged male and female were placed in a flight cage in the greenhouses on the top level of the museum parking garage. They paired the very first night they were together. During mating, the moths remained coupled for several hours. Then, over the next three days, the female laid approximately 150 crimson eggs, placing them indiscriminately along the walls and edges of the flight cage.

A mating pair of Atlas moths clinging to the side of a flight cage. The larger of the two is the female.

Atlas moth larvae are generalists, meaning they will feed on a wide variety of host plants (but not all plants). Hoping to determine which of several possibilities would be the best food for our caterpillars, we searched the literature for recorded host plants.

We chose four that we had available, including Camphor Tree (Cinnamomum camphora), Vitex (Vitex trifolia purpurea), Mahogany Tree (Swietenia mahoganii) and Sweet Potato Vine (Ipomoea batatas). Gathering the eggs, we divided them among four plastic containers lined with moist paper towels and ventilated with tiny holes poked in the lid, each containing a different kind of leaves.

The eggs took 10 days to hatch. The hatchling larvae were covered in pale protuberances and had black heads. After eating their eggshell, the tiny caterpillars began eating the provided foliage. Once the caterpillars were feeding reliably, they were moved to netted cages containing potted plants, so the leaves would be constantly fresh.

The caterpillars hatched on a Friday in September. To track their weekly growth and development, we took a photograph of them each Friday thereafter. It quickly became obvious that the caterpillars on Camphor were thriving: they grew bigger and faster than their siblings on the other plants (the pictures shown below are of larvae fed on Camphor). In each photograph, larvae were placed next to a standard sized Popsicle stick, fondly known as “Size Reference Ralph,” to track their relative growth.

The caterpillars took six weeks from hatching to pupation. They ate voraciously, becoming soft and fleshy to the touch, and were a pale blue-green color. Their backs were covered in a Mohawk of tubercles with a thick, waxy, flaky coating. After six weeks, the caterpillars were almost as long as Size Reference Ralph and were quite pudgy.

The sequential pictures show the dramatic changes in the larvae, followed by the start of silk spinning, and finally a complete cocoon. Once they finished their cocoons, the larvae pupated inside. We then gently moved the dried cocoons to the emergence chamber inside the entomology hall of the Butterfly Center.

Egg to cocoon in Atlas Moths. Pictures were taken one week apart next to Size Reference Ralph. (Pictures courtesy of Lauren Williamson)

Then we waited. Atlas moths may eclose from their cocoon in as little as three weeks, but can sometimes take several months. To escape from their silken enclosures, they must excrete a substance that dissolves a hole in the silk, allowing them to crawl out. They then cling to their cocoons while their wings expand and dry.

The first Atlas moth of our batch of cocoons emerged on Dec. 17, almost 3 months after hatching from the egg. It was a large female, with a wingspan of just over 10 inches. As you can see, Size Reference Ralph was dwarfed by her!

Know a girl who’s interested in math and science? Come to GEMS (Girls Exploring Math & Science) on Sat., Feb. 8 from 9 a.m. to 1 p.m. The Museum will be filled with hands-on science and math for everyone to experience. Local professionals will be at the Museum to answer questions about their careers in the fields of science, technology, engineering and math.

The Houston Museum of Natural Science was founded in 1909 – meaning that the curators of the Houston Museum of Natural Science have been collecting and preserving natural and cultural treasures for a hundred years now. For this yearlong series, our current curators have chosen one hundred exceptional objects from the Museum’s immense storehouse of specimens and artifacts—one for each year of our history. Check back here frequently to learn more about this diverse selection of behind-the-scenes curiosities—we will post the image and description of a new object every few days.

This description is from Nancy, the museum’s director of the Cockrell Butterfly Center and curator of entomology. She’s chosen a selection of objects that represent the rarest and most interesting insects in the Museum’s collections,that we’ll be sharing here – andat 100.hmns.org– throughout the year.

This spectacular, iridescently colored moth is considered by many to be the most beautiful of all Lepidoptera (the order of “scaly winged” insects, i.e., butterflies and moths). A day-flying moth endemic to Madagascar, it was originally described as a butterfly due to its resemblance to the swallowtails. The rainbow of colors on both upper and lower wing surfaces that make this species so sought after by collectors are not due to pigments, but result from the scattering and reflecting of light by microscopic ridges and pits on the highly curved scales covering the wings.

The museum has several hundred specimens of this moth. It is relatively common in its native habitat, where it periodically undergoes massive one-way migrations when the hostplants for the caterpillar stage (they feed on trees in the spurge family) increase the amount of distasteful toxins in the leaves. Interestingly, after the migration has lessened pressure on the hostplant, the amount of toxins in the leaves subsides to normal levels. In the American tropics, a close relative, the green Urania moth (Urania fulgens), also makes mass migrations for the same reason.

The Houston Museum of Natural Science was founded in 1909 – meaning that the curators of the Houston Museum of Natural Science have been collecting and preserving natural and cultural treasures for a hundred years now. For this yearlong series, our current curators have chosen one hundred exceptional objects from the Museum’s immense storehouse of specimens and artifacts—one for each year of our history. Check back here frequently to learn more about this diverse selection of behind-the-scenes curiosities—we will post the image and description of a new object every few days.

This description is from Nancy, the museum’s director of the Cockrell Butterfly Center and curator of entomology. She’s chosen a selection of objects that represent the rarest and most interesting insects in the Museum’s collections,that we’ll be sharing here – andat 100.hmns.org– throughout the year.

This relative of our luna moth (Actias luna) is native to conifer woodlands in the mountains of northern Spain, southern France, and parts of Switzerland. There is still some debate over whether this moth should be included in the genus Actias, or placed in its own genus (Graellsia). The species name honors Queen Isabela of Spain. This moth is fairly rare and populations are fragmented, so today it is protected by law in Spain and France and cannot be collected without a special permit.

Males and females are similar in color, but the male (right) has long tails much like our luna, while the stouter female (left) has much shorter tails. The caterpillars, handsomely patterned in green, brown, and white, eat various conifers, especially pine.

Well, it’s that time of year again… we have started to get Attacus atlas, aka Atlas moths, YEAH!!!! This is always an exciting time for me because I get to tell everyone who keeps asking me that they are finally here! Last week, I received 60 atlas moth cocoons from Malaysia and the Philippines. Unlike the butterflies we receive on a regular basis that all emerge within a few weeks, the atlas moths should be emerging over a few months, so we should have them for a while.

The Atlas moth belongs to the family of giant silk moths, Saturniidae. They are considered to be the largest moths in the world in terms of wing surface area. These impressive moths can only be found naturally in Southeast Asia, where they are very common. Their name comes from either the Titan of Greek mythology or from the striking pattern on their wings, which resembles a map. If you look at the tips of the forewings they resemble a snakes head, which makes for great predator protection.

The females are significantly larger than the males, especially their abdomen because she has to lay a bunch of eggs, which are already developed and ready to be fertilized. The males have larger, bushier antennae, in order to detect female pheromones.

The females
are larger and have bigger abdomens

The males are smaller and have longer antennae

Each moth starts it’s life as a beautiful, emerald-colored caterpillar. The larvae feed on a wide variety of food plants, and may even wander from one to another. As it gets bigger it developes a more waxy, light-white-ish green coloration. It then spins a silken cocoon to protect itself and pupates inside (This is different from butterflies who develop inside a chrysalis, not a cocoon). The adults, as in other Saturniids, have no mouth parts whatsoever, so they cannot feed. They survive off of fat reserves they build up as caterpillars.

Moths fly at night, so you may see these large moths resting on trees in the Butterfly Center during the day, paying no attention to the butterflies fluttering all around them. I try really hard each time a moth emerges to place it in a very obvious place so people can see them. Many people think they are fake because they sit so still, but now you know they are not!